Two recent randomized placebo-controlled trials show that gestational diabetes (GDM) treatment (vs. none) improves maternal and perinatal outcomes, based on diagnosis with a 2- step screening strategy. Also, a large multi-center prospective cohort study showed a linear relationship with glucose and maternal and perinatal outcomes, based on screening with a single 75g oral glucose tolerance test (OGTT). Based on this large cohort's findings, the American Diabetes Association recommended that clinical practice adopt the 1-step 75g screening approach for diagnosing GDM. The American College of Obstetrics & Gynecology took the opposite stance, recommending the traditional 2-step screening: because it alone has RCT outcome evidence. What is urgently needed in 2013 to best inform clinical practice and health policy is not an additional GDM treatment vs. control tria, but a pragmatic RCT testing the 2 recommended clinical strategies. To pragmatically address this critical research gap, we propose to randomize an estimated 17,626 diverse women to GDM screening (2-step vs. 75g OGTT) as part of their clinical care in the Kaiser Permanente Northwest (KPNW) and Hawaii (KPH) regional health plans. We will use the plans' electronic medical record (EMR) system at the time of GDM screening to randomize the women. Both KPNW and KPH regions universally screen for GDM at 24-28 weeks gestation, and they will cover the costs of randomizing women to the two approaches, as well as treatment per standard protocol, as part of clinical care. Importantly, our team will also leverage the strong partnership we forged with both regions' OB/GYN departments to carry out our current project that evaluates the Impact of Early Gestational Diabetes Screening in High-Risk Populations (R01 HD058015). By randomizing GDM screening in the context of clinical care, we specifically propose: to compare GDM prevalence's (Aim 1) and differences in maternal and perinatal outcomes between screening strategies (Aim 2). We also propose to determine the concordance of the 75g OGTT with GDM diagnosed by 2-step, among a recruited sub-sample of 1,000 pregnant women at KPNW and KPH. With our combined expertise in the GDM field and strong regional partnerships to support randomizing current universal GDM screening in KPNW and KPH as part of clinical care, we are exceptionally poised to fill the important research gap about these 2 screening strategies (2-step vs. 75g OGTT). Additionally, because of our KP health plan collaborations, we offer an extraordinary capacity to track and evaluate the impact of these screening strategies on outcomes in over 35,000 participants (>17,500 mother-child pairs). This proposal also offers the design advantage of testing aims in a real-world clinical setting. Results from our proposed pragmatic RCT truly have enormous potential to fundamentally and quickly transform clinical practice.